In recent years, with the development of multimedia, wireless terminals (smartphones and the like) in which an antenna for wireless communication, such as cellular and wireless LAN, is mounted are being actively produced. In the future, in particular, there is a demand for a wireless terminal that transmits and receives radio signals corresponding to IEEE 802.11ad, 5G cellular, and the like that use broadband signals in a millimeter wave band.
In a wireless terminal manufacturing plant, a performance test is performed in which the output level or the reception sensitivity of the transmission radio wave defined for each communication standard is measured for a wireless communication antenna provided in a wireless terminal to determine whether or not a predetermined standard is satisfied.
With the transition of generation from 4G or 4G advance to 5G a test method for the performance test described above is also changing. For example, in a performance test in which a wireless terminal for 5G new radio system (NR system) (hereinafter, a 5G wireless terminal) is a device under test (DUT), cable connection between the antenna terminal of the DUT and a testing device, which is a mainstream in tests of 4G 4G advance, and the like, cannot be used. For this reason, a so-called OTA test is performed in which the DUT is housed in a box, which is not influenced by the surrounding radio wave environment, together with a test antenna and transmission of a test signal from the test antenna to the DUT and reception of a measurement target signal from the DUT, which has received the test signal, by the test antenna are performed by wireless communication.
In the performance test of the 5G wireless terminal, a compact antenna test range (hereinafter, a CATR) is known as test equipment for realizing the OTA test environment described above. The CATR includes an anechoic box called an OTA chamber, and houses the DUT and the test antenna so that intrusion of radio waves from the outside and radiation of radio waves to the outside are prevented. In addition, in the CATR, a reflector having a paraboloid of revolution is arranged in the signal propagation path between the antenna of the DUT and the test antenna. Therefore, since the signal propagation path can be shortened compared with a case where no reflector is used, the CATR is characterized in that compactness can be literally realized compared with the OTA test in a general far-field environment.
In a measurement apparatus using the CATR, a test signal is transmitted from the test antenna to be received by the DUT in the OTA chamber, and a measurement target signal transmitted from the DUT that has received the test signal is received by the test antenna and the performance test described above is performed.
On the other hand, the 5G wireless terminal has a wide use frequency range. For this reason, in a case where the 5G wireless terminal cannot be covered by one test antenna at the time of measurement in a state in which the 5G wireless terminal is housed as a DUT in the CATR, it is necessary to prepare a plurality of test antennas that use a plurality of different frequency bands within the usable frequency range.
As a conventional antenna measurement apparatus using a plurality of test antennas, there is known a technique for simultaneously transmitting a plurality of beams with the same frequency, on which different codes are superimposed, through a multi-beam antenna and simultaneously measuring all beams radiated from the multi-beam antenna while suppressing the influence of unnecessary waves due to encoding on the plurality of beams with the same frequency (for example, refer to Patent Document 1).